Substituted ammonium salts



Patented Jan. 12, 1954 SUBSTITUTED AMMONIUM SALTS John W. Bishop, Plainfield, N. J assignor to Tide Water Associated Oil Company, Bayonne, N. 3., a corporation of Delaware No Drawing. Application August 11, 1950, Serial No. 178,999

13 Claims. 1

The present invention relates to a novel group of chemical compounds and, more particularly, to a group of substituted ammonium compounds having utility as rust-preventive agents for application to the surfaces of normally corrodible metals to inhibit corrosion and rusting thereof upon exposure to corrosive conditions such as highly humid atmospheres.

The novel compounds embodied herein may be broadly defined as substituted ammonium salts formed by an acid ester of a phosphorus acid with an esterifiabl alkylol-containing amine having an alkylol group esterified with a sulfonic acid. In addition to such compound per se, the invention also embodies such compounds in combination, such as in admixture or in solution, with an acid ester of a phosphorus acid, the presence of the free acid ester in such a combination being desirable in certain instances and particularly for contemplated use of the novel compounds as rust-preventives for ferrous metals exposed to extremely severe rust-inducing conditions.

In accordance with this invention, the acid ester component employed for formation of the novel salts embodied herein may be broadly defined as an ester of a phosphorus acid that contains at least one acidic hydrogen atom, i. e., a partially esterified phosphorus acid. For purposes of illustration. examples thereof include partially esterified compounds such as the monoand di-esters of phosphoric acid and mixtures of such esters. More specific illustrations are the aliphatic-, alicyclicand aryl-containing acid esters of phosphoric acid and, still more specifically, acid esters of phosphoric acid that contain as the residue of an es'terifying alcohol a hydrocarbon group containing a relatively large number of carbon atoms as, for example, from about four to about thirty carbon atoms. Illustrative of acid esters falling within such a group are aliphatic acid esters such as the Z-ethylhexyl acid phosphates, octyl acid phosphates, lauryl acid phosphates, mixtures of such aliphatic acid esters, alicyclic acid esters such as the cyclohexyl acid phosphates, e. g., monocyclohexyland dicyclohexyl-acid phosphates, arylol-containing acid phosphates such as the cardanyl acid phosphates, and the like.

As, the esterifiable alkylol-containing amine component suitable for use in formation of the substituted ammonium compounds embodied herein, the invention contemplates use of monotrialkylol amines such as triethanoland tripropanol-amines, alkyl alkylol amines such as ethyldiethanolamine, diethylaminoethanol, dibutylethanolamine and butyl-diethanol amine, cycloalkyl alkylol amines such as cyclohexyl-diethanol amine, aromatic-containing alkylol amines such as the Dhenyl alkylol amines, and the like. In preferred embodiment, tertiary alkyl alkylol amines such as the monoalkyldialkylol amines and dialkyl alkylol amines are employed, specific illustrations of which are included in the examples set forth hereinafter. It should be understood, however, that although such alkylol amines have been set forth as specific illustrations, the invention is not intended as being necessarily limited thereto, as in broad aspect the invention contemplates use of alkylol-containing amines that are esterifiable with a sulfonic acid to form esters suitable for formation of substituted ammonium compounds with acid phosphates as aforedescribed.

The sulfonic acid component of the novel compounds embodied herein'may be any of a. wide variety of sulfonic acids including such acids derived from petroleum and known to the art as petroleum sulfonic acids as well as sulfonic acids synthetically prepared by other means. Thus, the sulfonic acid component may be an aliphaticcontaining, aromatic-containing-, or mixed aliphatic-aromatic-containing sulfonic acid as illustrated by th lauryl-, stearyl-, benzyl-, and alkylbenzene-sulfonic acids as well as polysulfonic acids illustrative of which is a polymeric sulfonic acid having a molecular weight of about 3,300 and a neutralization equivalent of 390 and prepared from dodecyl'benzene and acetaldehyde monosulfonic acid. In further illustration, highly suitable sulfonicv acids for use in practice of this invention are the petroleum sulfonic acids known to the art as mahogany acids and generally formed when lubricating or similar petroleum fractions are treated with concentrated or fuming sulfuric acid. Such petroleum sulfonic acids are generally available in the form of their metal salt which are hydrolyzable to yield sulfonic acids suitable for esterifying alkylol-containing amines. Although, as aforesaid, a wide variety of sulfonic acids may be employed for esteriflcation of the alkylol-containing amines, particularly preferred are sulfonic acids having a relatively high molecular weight as, for example, a molecular weight of about 200 to about 600 as illustrated by sulfonic acids of the mahogany acid type as well as higher molecular weight acids, e. g., up to 3,500 or more, such as the aforesaid polysulionic acid prepared from dodecyl benzene and acetaldehyde monosulfonic acid. Sulfonic acids ventive compositions as the compounds embodied herein, which contain an alkylol amine esterlfied with a relatively high molecular weight sulfonic acid, generally possess improved solubility characteristics and in certain instances provide improved rust protective characteristics.

The substituted ammonium salts contemplated herein may be suitably prepared by mixing in desired proportions an acid ester of a phosphorus acid and an alkylol-containing amine that has an alkylol group esterifled with a sulfonic acid, and subjecting the mixture to addition reaction. The reaction between the esterified amine and acid phosphate proceeds rapidly with evolution of heat but without substantial, if any, evidence of byproduct formation such as gases, water, etc., to form a homogeneous, viscous reaction mass comprising the desired addition product. In order to expedite the addition reaction the mixture is preferably heated, such as to about 200 F. while maintaining the reacting mixture under agitation such as by stirring. Although no invention is claimed herein for the preparation of the sulfonic acid esters of the alkylol-containing amines, a suitable illustration thereof comprises preparation of a reactant mixture containing the alkylol amine and sulfonic acid in controlled concentrations for effecting the desired esterification and heating the mixture under reflux conditions for about two to four hours with use, if desired, of an esteriflcation catalyst such as sulfuric acid.

When the novel compounds as embodied herein are contemplated for use as rust-preventive agents by incorporating such compounds in a suitable vehicle, such as a mineral oil and fractions thereof, the novel compounds may be formed in situ by separately adding to such a vehicle an alkylol amine esterifled with a sulfonic acid and an acid ester of a phosphorus acid in an amount sumcient to form the substituted ammonium salts of the amine, the salt forming reaction being preferably expedited by heating the mixture with agitation as aforedescribed.

In order to further describe the invention the following examples are set forth for illustrative purposes with no intention that the invention be limited thereto.

EXAIMPLE I A mixture was prepared comprising p-toluene sulfonic acid and an amount of di-n-butyl ethanol amine in excess of the theoretical equivalent for esterifying the acid. The mixture was refluxed 4 viscous, amber-colored product soluble in a mineral oil of lubricating grade.

EXAMPLE II A mixture was prepared comprising a petroleum mahogany acid and diethyl amino ethanol for two hours, followed by heating the reacted mixture under vacuum to remove the excess unreacted amine and water of reaction to obtain ptoluene sulfonic acid ester of di-n-butyl ethanol amine. The esterifled alkylol amine was then mixed with lauryl acid phosphate in an amount theoretically equivalent to form substituted ammonium salts of the esterifled alkylol amine. The mixture, containing added xylene as a diluent, was stirred and subsequently heated for six hours at 125 C. to strip the reactant mixture of xylene whereby the lauryl acid phosphate salt of the p-toluene sulfonic acid ester of di-n-butyl ethanol amine was obtained as a homogeneous,

using an amount of the amine in excess of that theoretically equivalent to esterify the acid. The mixture was refluxed for two to four hours to form the mahogany acid ester of the amine with subsequent stripping of the excess amine and water of reaction from the reacted mixture. The

mahogany acid ester of diethyl amino ethanol was then mixed with lauryl acid phosphate in an, amount theoretically equivalent to form the substituted ammonium salt of the esterified alkylol amine and the mixture obtained was heated at C. for six hours in the presence of added xylene as a diluent to form the lauryl acid phosphate salt of diethyl amino ethanol esterifled with the mahogany acid. The reaction product was homogeneous, oil-soluble, dark-colored, of semi-fluid consistency, and glassy in appearance. With reference to the mahogany acid used in preparation of the aforesaid esterified allavlol amine, such an acid was obtained from "Petronate, a product well known to the art and containin*g,, about 60-65% of sodium salts of petroleum mahogany acids in a mineral oil. Petronate was dissolved in a 50-50 mixture (volume) of petroleum ether and the oil extracted from the sodium sulfonate by use of an ethanol-water solution. The substantially oil-free sodium sulfonate was then obtained by evaporation of the ethanol-water solution and the thus extracted sodium sulfonate was hydrolyzed with dilute hydrochloric acid using naphtha as a diluent with subsequent washing of the hydrolyzed mixture with a saturated sodium chloride solution to re-. move hydrochloric acid and minimize emulsiflcation. The hydrolyzed mixture was then stripped of solvent with obtainment of the substantially oil-free mahogany acid used in the aforesaid example for esterifying the alkylolamine.

EXAMPLE III A mixture was prepared comprising triethanolamine and an amount of a mahogany acid (as in Example II) theoretically equivalent to partially esterify the amine, i. e., an amount theoretically equivalent to esterify one ethanol group of the amine. The mixture was refluxed for two to four hours to produce the partially esterified triethan01 amine- The partially esterified amine was then mixed with an amount of lauryl acid phosphate theoretically equivalent to form the lauryl acid phosphate salt of the esterified alkylol amine and the mixture heated for six hours at 125 C. in the presence of xylene as a diluent with concurrent removal of the xylene to produce the lauryl acid phosphate salt of triethanol amine monomahogany sulfonate as a homogeneous, dark-colored product that was semi-fluid in consistency, of glassy appearance, and oil-soluble.

As aforesaid, the novel compounds embodied herein are particularly useful as rust-inhibiting agents and the use thereof in combination with a suitable vehicle to form rust preventive compositions is more fully described in my copending application, Serial No. 164,627 filed May 26, 1950. For purposes of illustration, the following table midity cabinet,

. conditions of the humidity corrosion test described in Army-Navy Aeronautical Specification Compound; Corrosive Preventive, Aircraft Engine AN-V'V-C-5'76B of April 28, 1945". Briefly the test comprises coating two freshly sand blasted steel panels with the test composition, draining for four hours in an atmosphere maintained at a relative humidity not exceeding 50% and a temperature of 25 plus or minus 3 C. and then subjecting the panels to a circulating atmosphere of 95 to 100% relative humidity at 120 F. for 150 hours or for a longer period to determine the corrosion inhibiting characteristics of the test composition under extended periods of corrosion and rust-inducing conditions. At the end of the test period the panels are removed from the hucleaned with naphtha, and examined.

7. A salt, as defined in claim 1, in admixture with a hydrocarbon acid phosphate.

8. An alkyl acid phosphate salt of an alkylolamine esterified with a hydrocarbon sulfonic acid.

9. A hydrocarbon acid phosphate salt of an alkylol-containing amine esterified with a hydrocarbon sulfonic acid, said salt being characterized in that the hydrocarbon group of the acid phosphate component contains about four to about thirty carbon atoms and the hydrocarbon sulfonic acid has a molecular weight of about 200 to about 600.

10. A salt, as defined in claim 9, wherein the alkylolamine is a tertiary alkyl alkylolamine.

11. A salt, as defined in claim 9, wherein the alkylolamine is a trialkyiolamine.

12. An acid phosphate salt of an alkylol-containing amine having an alkylol group esterified' Test compositions (by weight) Composition No 1 Mineral oil 97 Lauryl acid phosphate salt of mahogany acid ester of dibutylamiuoethanol Lauryl acid phosphate salt of mahogany acid ester of dibutylaminoethanol, and an 0.2 mole excess of lau'yl acid phosphate. Lauryl acid phosphate salt of trietlianolamine partially esterfied with mahogany acid, and with an 0.2 mole excess of lauryl acid phosphate Lam-yl acid phosphate salt of mahogany acid, and an 0.2 mole excess of acid phosphate Lauryl acid phosphate salt of with polymeric polysulfonic acid (mol. wt. of 3,300, neutralization e uivalent of 390 and prepared from dodecyl benzene and acet dehydc monosulionic acid), and an 0.2 mole excess of acid phosphate Dioctyl phosphate salt of the mahogany acid ester of dibutylaminoethanol R zistt prevention in hours under conditions oi aioredescribed Although the present invention has been described in conjunction with certain preferred embodiments thereof, those skilled in the art will readily recognize that variations and modifications can be made. Such modifications and variations are to be considered to be within the purview of the specification and scope of the appended claims.

I claim:

1. A hydrocarbon acid phosphate salt of an alkylol-containing amine having an alkylol group esterified with a hydrocarbon sulfonic acid.

2. A salt, as defined in claim 1, wherein the alkylol-containing amine is an alkyl alkylol amine.

3. A salt, as defined in claim 1, wherein the sulfonic acid is a petroleum mahogany acid.

4. A salt, as defined in claim 1, wherein the acid phosphate component of said salt is an alkyl acid phosphate, the alkylol-containing amine is an alkyl alkylolamine, and the sulfonic acid is a petroleum mahogany acid.

5. A salt, as defined in claim 1, wherein the alkylolamine is a tertiary alkyl alkylolamine.

6. A salt, as defined in claim 1, wherein the alkylolamine is a trialkylolamine.

with a hydrocarbon sulfonic acid, said salt being characterized in that its acid phosphate component is a member from the lauryl acid phosphates and octyl acid phosphates, the alkylol-containing amine is a member from the group consisting of dibutylethanolamine, diethylarninoethanol and triethanolamine and the sulfonic acid is a member from sisting of toluene sulfonic acids,

petroleum sul- -fonic acids and polymeric hydrocarbon sulfonic acids.

13. A salt, as defined in claim '1, wherein the hydrocarbon acid phosphate is an alkyl acid phosphate, the alkyl group of which contains about four to about thirty carbon atoms, and the sulfonic acid has a molecular weight of about 200 to about 3500.

JOHN W. BISHOP;

References Cited in the file of this patent UNITED STATES PATENTS Number 4 Name Date 2,233,001 Dickey Feb. 25, 1941 2,236,515 Cahn et a1. Apr. 1, 1941 Orthner -1- Mar. 9, 1943 group consisting of the group .con- 

1. A HYDROCARBON ACID PHOSPHATE SALT OF AN ALKYLOL-CONTAINING AMINE HAVING AN ALKYLOL GROUP ESTERIFIED WITH A HYDROCARBON SULFONIC ACID.
 7. A SALT, AS DEFINED IN CLAIM 1, IN ADMIXTURE WITH A HYDROCARBON ACID PHOSPHATE. 